Description: Hydrological modelling tools developed at INRAE-Antony (HYCAR Research Unit, France). The package includes several conceptual rainfall-runoff models (GR4H, GR5H, GR4J, GR5J, GR6J, GR2M, GR1A), a snow accumulation and melt model (CemaNeige) and the associated functions for their calibration and evaluation. Use help(airGR) for package description and references.
The **airGR** package implements semi-distributed model capabilities using a lag model between subcatchments. It allows to chain together several lumped models as well as integrating anthropogenic influence such as reservoirs or withdrawals.
`RunModel_LAG` documentation gives an example of simulating the influence of a reservoir in a lumped model. Try `example(RunModel_LAG)` to get it.
In this vignette, we show how to calibrate 2 sub-catchments in series with a semi-distributed model consisting of 2 GR4J models. For doing this we compare two strategies for calibrating the downstream subcatchment:
- using upstream observed flows
- using upstream simulated flows
We finally compare these calibrations with a theoretical set of parameters.
## Model description
```{r, warning=FALSE, include=FALSE}
library(airGR)
options(digits = 3)
```
We use an example data set from the package that unfortunately contains data for only one catchment.
```{r, warning=FALSE}
## loading catchment data
data(L0123001)
```
Let's imagine that this catchment of 360 km² is divided into 2 subcatchments:
- An upstream subcatchment of 180 km²
- 100 km downstream another subcatchment of 180 km²
We consider that meteorological data are homogeneous on the whole catchment, so we use the same pluviometry `BasinObs$P` and the same evapotranspiration `BasinObs$E` for the 2 subcatchments.
For the observed flow at the downstream outlet, we generate it with the assumption that the upstream flow arrives at downstream with a constant delay of 2 days.
The operations are exactly the same as the ones for a GR4J lumped model. So we do exactly the same operations as in the [Get Started](V01_get_started.html) vignette.
# Calibration of the downstream subcatchment with upstream flow observations
Observed flow data contain `NA` values and a complete time series is mandatory for running the LAG model. We propose to complete the observed upstream flow with linear interpolation:
rownames(mLag) = c("theoretical", "calibrated with observed upstream flow",
"calibrated with simulated upstream flow")
colnames(mLag) = c("LAG parameter")
knitr::kable(mLag)
```
## Value of the performance criteria with theoretical calibration
Theoretically, the parameters of the downstream GR4J model should be the same as the upstream one and we know the lag time. So this set of parameter should give a better performance criteria:
rownames(comp) <- c("Calibration of the upstream subcatchment",
"Calibration 1 with observed upstream flow",
"Validation 1 with simulated upstream flow",
"Calibration 2 with simulated upstream flow",
"Validation theoretical set of parameters")
knitr::kable(comp)
```
Even if calibration with observed upstream flows gives an improved performance criteria, in validation using simulated upstream flows the result is quite similar as the performance obtained with the calibration with upstream simulated flows. The theoretical set of parameters give also an equivalent performance but still underperforming the calibration 2 one.